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1. Technical Field
This invention relates to the field of computer software systems. More specifically the invention relates to the construction and implementation of a system for seamlessly injecting additional processing capabilities to an existing target software application, and injecting additional user interface features to the target application user interface, without modification of the source code for the target application.
2. Description of the Related Art
There are presently available a wide variety of computer software application programs to enable computer users to perform a various specialized task. For example, software application programs exist which can perform word processing, spread-sheet analysis, scheduling, and a multitude of other common tasks associated with business and technology. These programs are developed to satisfy certain well known requirements of a group of users, and are generally designed to offer capabilities which satisfy all of the tasks normally associated with such requirements. To this extent, the commercial application programs which are generally available to the public are quite satisfactory.
Occasionally, however, certain users may have specialized needs which have been either overlooked by software developers or which have been intentionally ignored, because implementation of functional features to address such needs has been deemed uneconomical, given the relatively small number of users who have a requirement for them. Alternatively, certain functional features may not be present in existing software applications programs because the technology to implement such features has not previously been available or is beyond the expertise of a particular software application developer. One example of a functional feature having both of the foregoing characteristics is speech recognition technology, or the ability of a software application to recognize spoken words. Speech recognition is a highly complex technology requiring significant specialized expertise on the part of the developer. On the other hand, the need or demand for this technology may not be sufficiently widespread at this time so as to provide clear economic justification for an individual computer software application developer to generally include the feature in software application products.
Where a particular commercial software developer chooses not to implement a particular product feature, such as speech recognition, in an application program, third party software developers may wish to independently provide such feature or functionality. In such cases, it would be desirable for the third party software developer to be able to develop and offer such functionality. Likewise, it would be desirable for such third party developers to be able to seamlessly integrate the new function into a graphical user interface (GUI) of the existing application""s user interface. In this regard, it should be understood that, as used herein, the phrase xe2x80x9cseamless integrationxe2x80x9d means that the user interface for the additional functionality to be added to a particular application, appears to a user to be an integrated or cohesive part of the existing software application""s user interface, and not as a separate window or separate program.
Significantly, however, seamless integration of additional software functions and features within the context of an existing application""s GUI creates several problems. Specifically, modification of a software application program to seamlessly implement an additional function within the context of the existing GUI generally requires access to the program""s source code. This requirement can present an insurmountable obstacle to implementation of the desired feature, as software owners are often quite reluctant to allow third parties to have access to source code for an application program. At a minimum, the need to have access to a software application""s source code, along with the owner""s permission to modify such code, will inevitably cause delays and added expense.
Accordingly, it would be desirable to provide a method for integrating one or more new functions to an existing target application program, and for adding one or more features to a GUI of an existing software application program. It would also be desirable to provide a method and system for seamlessly injecting a new function and/or a user interface feature into an existing software application program, without access to, or modification of, the source code for such existing software application program.
This invention solves the aforementioned problems in the context of an operating system wherein each application program resides in a process address space which cannot be directly accessed by another application program. More particularly, the method provides a method and apparatus for seamlessly integrating new functionality to an existing target application program. It also permits seamless integration of modified user interface features to a GUI of an existing target application program. Significantly, the disclosed invention does not require access to the existing application program""s source code in order to accomplish the foregoing results. Rather, the disclosed method and apparatus provides an approach which allows a technology injection system (TIS) to inject itself directly between a computer operating system and the target program so as to intercept messages and commands to the target program. In this way, the TIS can modify any inputs and outputs of the target program. By intercepting and then performing special processing of those messages to the target application which relate to the new functionality and/or which determine the appearance of the target application user interface, the TIS can implement the new functional features and seize control over the appearance of the interface.
Interception of messages between the operating system and the target application program is achieved by utilizing a combination of techniques which take advantage of available operating system functions, to insert a surrogate window procedure contained in a Dynamic Link Library (DLL), into the process address space of the target application program. Upon command from the TIS program, the surrogate window procedure initiates a sub-classing process whereby a pointer to the target application program""s main window procedure is overwritten with a new pointer to the surrogate window procedure. Depending upon the nature of the functional or interface modifications to be implemented, such modifications may be performed directly by the surrogate window procedure, i.e. if permitted by the operating system architecture, or by an emulation window procedure residing in the TIS program. In a preferred embodiment, messages are transmitted between the primary and secondary window procedures, by manipulating existing operating system functions to overcome system architecture limitations which would normally prevent functional and user interface modifications to a target application program.